49ers rookie running back Marcus Lattimore sprints down the field during minicamp in June. / Ed Szczepanski, USA TODAY Sports

by Tom Pelissero, USA TODAY Sports

by Tom Pelissero, USA TODAY Sports

As expected, Marcus Lattimore will be a spectator when the defending NFC champion San Francisco 49ers open training camp next week.

The team announced Saturday that Lattimore â?? a running back from South Carolina who suffered a gruesome knee injury last fall â?? will open training camp on the active/non-football injury list.

That designation means Lattimore will count against the 90-man roster limit and can be activated at any time before final cuts, though he's expected to miss most, if not all, of his rookie season.

Days before the draft, Lattimore pledged to be ready by Week 1 of the NFL season, though he knew his status would be decided by his future team.

"I know my body," Lattimore told USA Today Sports. "I know when I'll be ready to play. It takes time, I know, but at the beginning of the season, I feel like I should be ready to go."

He landed on the non-football injury list, not the physically unable to perform list, because the injury occurred before the 49ers drafted him in the fourth round (131st overall) in April.

Lattimore, 21, amassed 3,444 yards from scrimmage and 41 touchdowns in three seasons with the Gamecocks. He decided to forgo his senior year despite damaging several ligaments on a hit in a game against Tennessee on Oct. 27 that left his right leg bent in an abnormal direction.

Not listed was receiver Michael Crabtree, who tore an Achilles tendon during organized team activities in May and could be a candidate for injured reserve with designation to return.

Rookies reported to 49ers camp Friday. Veterans are due to report Wednesday.

Lattimore said he's looking forward to learning from 49ers running back Frank Gore, who reached out to him when Lattimore first injured his knee last year. A year after suffering a torn anterior cruciate ligament in his left knee, Lattimore had reconstructive surgery Nov. 2, performed by renowned surgeon James Andrews, to repair the anterior cruciate, lateral collateral and posterior cruciate ligaments in his right knee. Gore, too, was damaged goods coming out of college.

"Right after it happened, I doubted myself and I lost hope," Lattimore told USA Today Sports after the draft. "But one of my good friends came over, I got a chance to talk to Frank Gore, I got a chance to talk to Willis McGahee, and I realized God doesn't make mistakes. Now I'm with the 49ers. It's just a great, great situation for me."